John Munson/The Star-LedgerThe Mets added a star in Jason Bay, but a lack of depth could exacerbate the effect of injuries, as the team learned last season.CAN THEY POSSIBLY STAY HEALTHY?

This would be a big issue for any team coming off the kind of year the Mets had in 2009. But the need for the Mets to avoid injuries -- and to manage them better when they do happen -- is even more pressing because of what they have done this winter. Or, rather, what they haven't done.

The Mets are not lacking in star talent. If Jose Reyes, Johan Santana and Carlos Beltran make full recoveries from their injuries and David Wright and Mike Pelfrey rebound from what was a disappointing 2009, the Mets have the pieces to at least be in the wild-card conversation.

But their failure to acquire better complementary players leaves the roster thin at some key positions going into spring training. They added a star in Jason Bay and several much smaller pieces, but not a lot in between. And that area in between is where the Mets are lacking.

What does a lack of depth have to do with health? It exacerbates the effect of injuries, as we saw last year.

There are reasons to believe the Mets have the potential to be competitive. They just need a lot to go right, starting with an area where so much has gone wrong: injuries.

WHO FILLS OUT THE STARTING ROTATION?

The title of the Mets' promotional campaign for 2010 is: "We believe in comebacks." And that's essentially all they can do with their rotation. They didn't upgrade it at all, so they are left to hope and believe that Pelfrey will have a dramatic turnaround, Oliver Perez will start living up to his contract and John Maine will be fully healthy for the first time since 2007.

Their fifth starter is no sure thing, either. A group that includes Jon Niese, Fernando Nieve and Hisanori Takahashi will compete for the job in spring training. But if their No. 5 starter ranks among their top concerns in a few months, they'll be in good shape.

First, they need to get enough out of Pelfrey, Perez and Maine for the fifth starter to even matter.

CAN THEY GET BETTER ON DEFENSE?

By just about any measure, the Mets were among the worst defensive teams in baseball last year. They didn't just make errors. They made full-blown, blooper-reel gaffes. Much of that had to do with injuries, but not all of it. That's why manager Jerry Manuel said defense, along with pitching, will be his primary focus in spring training. Last year Manuel stressed offense and an opposite-field approach. By the time he decided to address the Mets' defense in May, it was too late. This year, defensive fundamentals will be stressed from the first day of camp.

KEY DATES

Thursday: Pitchers and catchers reportSaturday: First workout for pitchersFeb. 23: Position players reportFeb. 25: First full-squad workoutMarch 2: First Grapefruit League gameApr. 3: Final Mets exhibition gameApr. 5: Opening Day

NOTABLE ADDITIONS

OF Jason Bay: The lone major acquisition in an otherwise quiet offseason, Bay becomes more important now with Carlos Beltran out.

RHP Kelvim Escobar: Has pitched in just one major-league game since 2007 but is said to be healthy now and ready to compete for the setup role in the bullpen.

OF Gary Matthews Jr.: Will compete with Angel Pagan for the starting center field job until Beltran returns.

P Hisanori Takahashi: Not to be confused with Ken Takahashi, who pitched for the Mets last year, this Takahashi will compete with several others for the fifth spot in the rotation.

NOTABLE SUBTRACTIONS

RP J.J. Putz: Signed with the White Sox after Mets declined to pick up his option for 2010.OF Gary Sheffield: Remains an unsigned free agent. Mets had no intention of bringing him back.1B Carlos Delgado: Still looking for work after stint in winter ball raised concerns about his mobility in the field.C Brian Schneider: Signed a two-year deal with Philadelphia, where he'll back up Carlos Ruiz.